1. Field of the Invention
This invention relates to a method for the disposal of a waste material from a process for production of acrylic acid and a process for production of acrylic ester, and further from a process for production of polyacrylic acid. More particularly relates to a method for the disposal of the waste material, specifically the waste oil, waste water, and waste gas emitted from the process for production of acrylic acid, the waste oil, waste water, and waste gas emitted from the process for production of an acrylic ester, and further the waste water and waste gas emitted from the process for production of polyacrylic acid (salt), by combustion of the waste material aimed at preventing the piping of a combustion furnace from blocking and the interior of the furnace from generating a blocking material thereby fulfilling environmental conservation of marked advantage.
2. Description of the Related Art
Acrylic acid is a versatile chemical substance and is generally produced on a large scale by the reaction of catalytic gas phase oxidation of propylene, for example. Since this reaction of catalytic gas phase oxidation yields low boiling substance, high boiling substance, etc. as secondary products besides forming acrylic acid, the acrylic acid is purified by removing them in various steps. The impurities which have been separated and removed during the process for obtaining an object from a raw material, therefore, are discharged as waste gas, waste water, waste oil, etc from the process. The waste gas and the waste liquid which are discharged from the process of a commercial scale are proportionately large amounts.
Such waste material as the waste gas and the waste liquid is required to be purified in a high degree and disposed from the viewpoint of preventing the environment from being polluted and the cost for the purification of such waste material is required to be decreased in order to repress the total cost of production. As a technique for accomplishing these requirements, the official gazette of JP-B-63-67,090 discloses an apparatus for the disposal of the waste gas by using a heat exchanger. The official gazette of JP-B-07-112555 discloses a method for the disposal of a waste water containing not only an organic acid but also an ester and an aldehyde thereof by a treatment with an alkali, concentration, and incineration. This method comprises the steps of adding an alkaline substance to the waste water until the resultant pH value reaches a level of not less than 12 thereby inducing a reaction capable of deriving an involatile compound and a volatile compound, removing at least part of the volatile compound by gasification, further concentrating the remaining waste water, and thereafter burning the concentrate. In view of the adverse situation that since the waste water resulting from the neutralization of an acidic substance intermittently emits an organic acid, the resultant condensed water suffers the COD thereof to rise to the extent of rendering a biochemical treatment difficult to effect necessary disposal, the invention of this official gazette contemplates providing a method for the disposal of the waste water by separating a volatile organic acid and an involatile organic acid and adjusting the COD value in a range allowing the disposal to be fulfilled effectively.
The official gazette of International Unexamined Patent Publication No. 2000-514419 discloses a technique which comprises burning a gaseous low boiling component by-produced during the production of (meth)acrylic acid and supplying the other component such that the low boiling or medium boiling component which is dissolved in water and added to the step of burning the gaseous low boiling component. This invention concerns a method for discarding the second component of a low boiling, medium boiling, and high boiling substance formed in the production of (meth)acrylic acid and characterized by burning the gaseous low boiling second component and meanwhile adding the low boiling and medium boiling second component dissolved in water together with the high boiling second component.
The produced acrylic acid is used as a raw material for various chemical products. The acrylic acid obtained from an acrylic acid producing plant is supplied to an acrylic ester producing plant or water absorbing resin such as polyacrylic acid producing plant, which is built at the same place or adjoining the site of the acrylic acid producing plant and put to production therein in a continued process. When an acrylic ester or polyacrylic acid is produced at the same place or adjoining the site for the acrylic acid producing plant, the process for the production of the acrylic ester and the process for the production of the polyacrylic acid also emit such impurities as waste gas, waste water, and waste oil. These plants desire to employ a technique capable of efficiently purifying these impurities in a high degree and disposing them.
As such a technique, the official gazette of JP-A-53-142057 discloses a method for purifying an alkali salt-containing waste water emanated from an acrylic ester production process. In a process for recovering acrylic acid from a gas phase mixture obtained by the reaction of catalytic gas phase oxidation of propylene or acrolein, purifying and esterifying the recovered acrylic acid, subjecting the produced mixture to alkali cleaning, and eventually recovering an acrylic ester, the method of this official gazette comprises exposing the gas phase mixture to the waste water of alkali cleaning heated in advance to a temperature higher than the gas phase mixture thereby causing the water component contained in the waste water to vaporize into the gas phase mixture or subjecting the waste water of alkali cleaning which has decreased the water content to disposal by incineration. This method treats the gas phase mixture and the waste water of alkali cleaning separately.
The method which is disclosed in the official gazette of JP-A-53-142057, however, is directed exclusively toward the gas phase mixture and the waste water of alkali cleaning and is not sufficient to dispose of other waste.
Generally, when the waste oil discharged in a process for the production of acrylic acid is burnt, since acrylic acid has high viscosity, the waste oil disposed of as it is by the combustion tends to clog the piping of the combustion furnace. When the waste oil is used as the fuel for the disposal by incineration, the incineration suffers from such problems as encountering difficulty in ensuring just enough supply of the fuel and entailing possible excess generation of combustion energy. It is further at a disadvantage in inducing the incinerator to form a deposit on the inner wall thereof and consequently causing the incinerator to undergo accelerated deterioration and, when the waste gas arising from the incineration is burnt by itself, causing the heat exchanger used for the burning to yield to corrosion readily and rendering the combustion itself difficult to carry out. The waste gas, similarly to the waste liquid, has the possibility of forming a deposit on the inner wall of the heat exchanger and consequently curtailing the service life of the heat exchanger.
This invention has been initiated with a view to solving the problems and is aimed at providing a method for enabling the waste gas, waste oil, and waste water emitted from the process for production of acrylic acid and the waste gas, waste water, and waste oil emitted from the process for production of acrylic acid, acrylic ester and/or polyacrylic acid (salt) to be purified in high degree and disposed jointly.